This invention relates to apparatus for applying surgical staples and other surgical fasteners, and more particularly to such apparatus having a longitudinally flexible shaft intermediate the portion of the apparatus which performs the stapling function and the actuator portion of the apparatus. (For simplicity, discussion will hereinafter be confined, in terms, to surgical staplers, but it is to be understood that the scope of the invention extends to apparatus for applying any type of surgical fasteners.)
There are several known types of surgical staplers in which the stapling function takes place at a location which is relatively remote from the location at which the stapler is held and actuated by the operator. Examples of such staplers are the linear closure surgical staplers shown illustratively in Green et al. U.S. Pat. No. 3,494,533 and the circular anastomosis surgical staplers shown illustratively in Conta et al. U.S. Pat. No. 4,304,236. Typically, in instruments of the types exemplified by these patents, tissue to be stapled is clamped between an anvil assembly and a staple holding assembly, both of which are located at the distal end of the instrument. The clamped tissue is stapled by driving one or more staples from the staple holding assembly so that the ends of the staples pass through the tissue and are clinched by contact with the anvil assembly. The forces required to operate the instrument are applied by the operator of the instrument to one or more actuator elements located at or near the proximal end of the instrument. The distal and proximal portions of the instrument are joined by a longitudinal connecting shaft structure along which the actuating forces and motions are transmitted to the distal operating elements. This type of construction, including relatively widely spaced distal and proximal portions, may be employed for any of several reasons, such as the relative inaccessibility of the tissue to be stapled, the need for good visibility of the tissue during stapling, and the like.
In some applications of instruments of the types mentioned above it may be desirable for the longitudinal shaft structure joining the distal and proximal portions of the apparatus to have at least a section which is longitudinally flexible. This may facilitate placement of the instrument in particular body structures, it may facilitate reaching remote or relatively inaccessible stapling sites, or it may allow the staples to be presented at the stapling site at various angles relative to the operator of the instrument. However, this type of instrument construction means that the actuating forces and motions must be transmitted through a flexible structure capable of taking on a variety of curvatures. This considerably complicates the design of the instrument. In addition to transmitting actuating forces and motions through a variety of curvatures, the structure must generally transmit these forces and motions without significant straightening, and without significantly greater frictional losses than would be present in a comparable straight instrument. Both the control of the tendency to straighten and the control of friction losses are much more difficult in a flexible instrument than in a comparable rigid instrument.
In view of the foregoing, it is an object of this invention to provide improved surgical staplers having a flexible shaft structure between the distal stapling elements and the proximal actuating elements.